Counter-terrorism police are investigating a suspected arson attack at a former synagogue.
The fire was reported at 05:16 BST on Tuesday at the former East London Central Synagogue building in Whitechapel.
The Met said initial CCTV footage indicated the fire was started deliberately.
The suspected arson follows a series of attacks and attempted attacks on the Jewish community in recent weeks.
Det Ch Supt Brittany Clarke, who leads policing in the area, said the force was taking this incident "extremely seriously" and would be working with colleagues from counter-terrorism policing.
She added: "The building targeted has not been operational as a synagogue for some years but that will be of little comfort to the Jewish community in Tower Hamlets, Hackney and beyond, who are first in my thoughts this morning."
Cdr Helen Flanagan, the head of counter-terrorism policing, said officers were looking at potential links between this incident and recent attacks on the Jewish community in north and north-west London.
She said officers were providing "security advice and support" to various organisations, community venues and businesses.
"With the threat level now raised to severe, everyone can play their part to keep themselves and their communities safe," Flannagan added.
A London Fire Brigade spokesperson said crews had put out "a small fire affecting the exterior of the building" and the cause is being investigated alongside the Met Police.
There were no reports of any injuries.
The Community Security Trust (CST), a group that provides security within Jewish communities, said it was aware of the incident and urged people "to remain vigilant and to report any suspicious activity, at any time of day or night".
The Ashaadibi Education and Cultural Centre, which is in the process of buying the building, condemned the arson attack.
In a letter posted on their website and on social media, the organisation said: "We are deeply saddened to learn of the arson attack at the Nelson Street Synagogue in east London this morning.
"We unequivocally condemn this cowardly act of arson and any form of violence or intimidation directed at places of worship and the communities they serve.
"An attack on a house of worship is an attack on all of us," the letter said.
"There is no place for hatred in our borough."
A Downing Street spokesperson said the arson appeared to be the latest in a "series of deeply shocking and disturbing incidents targeting the Jewish community".
He added he could not go into specifics but it was "natural" for the prime minister to be kept updated on any issue of this type and the government was taking antisemitism extremely seriously, with a summit held on Tuesday morning.
Leon Silver, 76, the president of the former synagogue, said he felt "awful" after hearing about the attack and "found himself trembling".
"I mean it's an awful thing to happen – and in Tower Hamlets," he said.
"We have had incidents here over the years, passers-by shouting, but nothing on this level, someone trying to burn the synagogue."
He said that the fire had not spread beyond the gates but believed there had been an attempt to get in through the window, which was prevented by the "wide grilles in front" stopping it from being smashed.
Hamzah, who lives near the former synagogue - which he believes is being turned into a mosque - said: "I came out this morning and saw it was all blocked off... I heard there was a firebomb on the synagogue."
He added that he did not know why someone would do that.
A woman who also lives in the area told Radio London it was "horrible" for the attack to happen.
"Honestly, I wouldn't expect it to happen here of all places," she said.
Another woman added: "Any hate crime is not something that should be done. It's sad."
The former synagogue was due to be sold at auction earlier this year, with a separate bid by a Muslim group to buy the building and convert it into a mosque and community centre.
Since late March there have been a series of arson attacks at Jewish sites in London, as well as a double stabbing in Golders Green that is being treated as an act of terrorism.
Most of the attacks have been claimed by a purported group called Hayi.
Propaganda messages using that name have appeared on social media channels associated with the Iranian regime - but counter-terrorism investigators have not ruled out that these may be opportunistic claims.
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